1. Field of the Invention
The present invention relates generally to heat-dissipation techniques, and more particularly to a heat sink having an improved structure, which can prevent solder from being absorbed by a metal capillary wick while manufacturing the heat sink.
2. Description of the Related Art
As shown in FIG. 1 and FIG. 2, a conventional heat sink is partially composed of a top shell member 91, a bottom shell member 92, and a capillary wick 93. A vapor chamber is formed between the two shell members 91 and 92, and the capillary wick 93 is received inside the vapor chamber for effectively exchanging heat via the coexistent effect of vapor and liquid. While the two shell members 91 and 92 are connected with each other, a soldering bar 95 is disposed at seams of the two shell members 91 and 92 and is melt by heating to flow into and jam the seams so as to further interconnect the two shell members 91 and 92 tightly.
However, the aforementioned prior art still needs to be improved for some disadvantages. Specifically, the aforesaid capillary wick 93 is positioned tightly against an inner periphery of the vapor chamber at an outer peripheral fringe thereof, i.e. the capillary wick 93 is very close to the seams of the two shell members 91 and 92. Accordingly, after the solder 95 is melt, as shown in FIG. 2, the solder 95 will infiltrate the seams and then contact the capillary wick 93 to be further absorbed by the capillary wick 93, thereby causing the following disadvantages.
1. The solder is mostly absorbed by the capillary wick 93 and then fails to completely seal the seams of the two shell members 91 and 92, and thereby the heat sink is in malfunction.
2. To improve the above first disadvantage, greater amount of the solder will be used to seal the seams, but the capillary wicks 93 will partially lost capillary function because of absorbing great amount of the solder, thereby resulting in ineffective heat dissipation.
The primary objective of the present invention is to provide an improved heat sink, which seals seams between a base member and a cover member to further prevent solder from being absorbed by a capillary layer and to prevent the capillary layer from losing capillary function while manufacturing the heat sink.
The foregoing objective of the present invention is attained by the improved heat sink, which is composed of a base member, a cover member, at least one capillary layer, a plurality of hollow columns, a plurality of cooling fins, and a predetermined amount of solder. The base member is provided with an external wall extending upwards and outwards from a peripheral fringe thereof. The cover member is provided with a skirt portion extending downwards and outwards from a peripheral fringe thereof, a plurality of through holes, and a plurality of internal walls respectively extending upwards from a top side of the cover member at a peripheral fringe of the through hole. The cover member is mounted on the base member and the skirt portion is located within the external wall. A vapor chamber is formed between the cover member and the base member. The capillary layer, which is mounted in the vapor chamber, includes at least one plate member and a plurality of convex portions dividing the vapor chamber into a plurality of flow passages in communication with one another. The capillary layer is spaced apart from the skirt portion at a predetermined distance. The hollow columns are identical to the through holes in numbers and respectively have an end fitted onto the internal wall. Each of the hollow columns is fitted with a capillary pipe inside, which has a bottom end extending into the vapor chamber and connected with the capillary layer. The capillary pipe is provided with a plurality of pores at the bottom end thereof for intercommunicating the flow passages and the capillary pipes. A position in which an inner periphery of the hollow column contacts a top fringe of the internal wall is spaced apart from the capillary pipe at a predetermined distance. The cooling fins are fitted around an outer periphery of the hollow columns and are spaced apart from one another at a predetermined distance. The solder fills between the skirt portion and the base member and between bottoms of the hollow columns and tile cover member.